Grid lead-in construction



June 27, 1933. 1 E MOURQM'TSEFF 1,915,863

GRID LEAD-IY CONSTRUCTION Filed NOV. 2, 1927 mgl.

INVENTOR Illa E/Waz/ramseff Z,

'ATTORNEY Patented June 27, 1933 UNITED STATES ILIA E. MOUROMTSEFF ANDGREGORY V. RYLSKY, OF WLKINSBURG,

rnNNsYLvANrA,

ASSIGNORS TO WESTNGl-OUSE ELECTRIC AND MANUFACTURING COMPANY, A

CORPORATION OF PENNSYLVANIA GRID LEAD-IN CONSTRUCTION @ur invent-ionrelates to space-current devices and particularly to devices of thatcharacter adapted for short-wave radio service.

One of the. objects of our invention is to tti provide a constructionfor the in-leading wires to the control electrode or grid of ashort-wave radio tube.

Another object of our invention is to provide a means for feedingcurrent uniformly l' to all parts of the control electrode of a radiotube.

Another object of our invention isA to provide a structure which' shalldistribute, as uniformly as possible, the high-frequency iii electricand magnetic fields due to currents in the grid circuit of a short-waveradio tube.

A further object of our invention is to provide a .method for sealing inthe conductors leading to the grid of a radio tube withf out oxidizingthe parts within the tube during such sealingoperation.

Other objects of our invention will become apparent through reading thefollowing specification, taken in connection with "T the accompanyingdrawing, wherein Figure 1 is a mid section of a portion of a radio tubeembodying our invention and Fig. 2 is a detail view showing the conjstruction of 'he in-leading wire at the time 53 it is ready to be sealedinto the tube.

In radio tubes, at the frequencies now commonly used in broadcasting,the current in the in-leading wire to the control electrode is usuallyof small magnitude, since it is merely the charging current for thatelectrode. However, the magnitude of such a charging current increaseswith the frequency of the current being employed and, in tubes designedfor so-called short-wave service, this charging current becomes ofconsiderable magnitude. This is particularly true in tubes of the largersizes which are used as transmitters in broadcasting.

r As a result of the increase in charging current, a problem arises inthe way of providing an in-leading conductor which shall be capable oftransmitting such a current to the control electrode. The grid leadstructure of tubes that operated satisfactorily on 750 lilocycles becamered and white Application led November 2, 1927. Serial No. 230,572.

hot and in danger of breaking at any moment when the tubes were operatedat 6000 liilocycles and above. ln the case of many tubes, therequirements of electrical insulationniake it necessary that theiii-leading wire shall pass through the tube wall at some distance fromthe control electrode itself.

@ne preferred form of supporting structure for the control electrodes oftransmitting tubes consists of a reentrant stem projecting into the tubefrom one end and consisting of a projection from `the press whichcontains the in-leading wires for the cathode. On such a reentrant-stemis mounted a metallic collar which may be clamped thereto and from whichthe wires supporting lthe control electrode project. ln thecase of thevery high-frequency currents employed in short-wave work, it isnecessary to make provision that the current shall be distributed asuniformly as possible `among the four support-stays of the controlelectrode.

In accordance with our invention, 'accordingly, we provide that thein-leading wires transmitting current to the control electrode shallconnect to the collar at points diametrically opposite to each other.

Referring to the drawing, Fig. 1 is a view partly in section, showingthe glass wall portion 1 of `a high-power transmitter tube.

art of the wall portion of this tube consistsof a meta-l anode Q, theactive portions of the grid 15 and cathode 16 being within the anode..The portion l has a reentrant stem 3, on which the collar 4, supportingthe grid on projecting rods 5, is clamped.V In leading wires 17 passthrough a press near the middle of the stern 3 and project into theanode 2 to support the cathode therein. Such a method of construction iswell known and needs no extended description.

The lead 6 to conduct current through the tube wall to the grid ispreferably sealed through the former at a point near the endof the tube.In accordance with our in vention, we provide a pair of'conductors 7 ofribbon form which are welded to diametrically opposite points on thecollar 4 and curve downward and `toward each otherso that' they may beconnected to the lead 6 which is located near the end of the tube and ata point on the circumference 90o displaced from each of these points ofconnection to the grid.

5 The double curvature of thek ribbonleads make them flexible andyielding to stresses longitudinal therein due to thermal expansion andthereby relieves the lead 6 from stress. We have found that a convenient1G method for connecting the lead 6 to the ribbons 7 is to weld to thelatter a member 9, shown most clearly in Fig. 2, which may be of copperand which is provided with a threaded hole. One convenient way ofattaching ribbons 7 to member 9 is to make the latter in the form of ahollow bolt which may b-e passed through holes in ribbons 7. A nut 11may then be screwed down binding mem- *bers 7 and 9 together. VThe tworibbons on 2G the clamp l form a triangular structure that is very rigidin respect to th-e twisting action of the nut 11 while it is beingattached thereto. The connection between the two may n T then berendered additionally secure by welding them together.

The containing vessel 1 may be of any suitable vitreous material, butthe one which we prefer to use is a glass known to the trade n"`as G702Pglass. The properties of this glass are such that it will make avacuumtight seal with conductors of tungsten or molybdenum. If theiii-leading wire 6 is made of molybdenum its end may be readily 9:'threaded to engage the threaded portion of N the member 9. In case,however, a tungsten in-leading wire is used, diiiiculty will be found inthreading its end.

We have found that a tungsten lead may By whatever method the threadedportionV is provided on the in-leading wire, the'latter may be sealedinto the tube by the following method. The anode 2 is first sealed tothe outer glass wall-portion 1. A hole with a raised rim 13 is blown atthe desired location inthe wall. The stem 3 is then constructed and thecathode filament mounted thereon. W' The ribbon members 7 are affixed tothe d" threaded member 9`in such vposition as to form substantially aletter V diverging therefrom. The ends are then flexed toward each otherand welded to diametrically opp posite points on the collar 4. Theresulting @d structure isrthen cleansed of any adherent oxides byheating it in a hydrogen atmosphere or by any other well-known methodand clamped in position on stem 3. Jg, The tungsten in-leading wire 6,having the GE' threaded portion formed thereon, is providbe providedwith a threaded portion by weld-V ed with a flange or collar 14 of glassof proper diameter and location to seal to the rim 13. This wire is thenfreed from any oxide produced by the glass blowers fires, by dipping itin sodium nitrite, for example. The stem 3 with the'cathode and gridelectrodes mounted thereon as already described is sealed into container1, with the threaded hole j in member 9 alined Ywith the hole in the rim13 of the tube wall. The tungsten lead 6 is then inserted through thelatter and screwed firmly into 'position in the threaded member 9. Aseal vmay then be readily made by the in diameter and 3 centimeterslong. The flexible ribbons 7 which are Welded to this collar il,consistof molybdenum ribbon 0.025 cms.r thick by 0.75 cms. wide andkapproximately 8 cms. long. Adjacent ends of these ribbons are welded toa molybdenummember 9, shown in detail in Fig. 2, which is 1.1 cms. longby 1.2 cms. in its largest diameter. The

As a specific example,r

tworibbons 7 form the sides of this V and diverge at an angle of60'degrees. These ribbons substantially follow the cuive of acylindrical surface that would be tangent to the face ofthe nut 11 andwould extend 90 around the stem 3 to intersect with the face of theclamp 4. The particular advantage of this shape is that elongation dueto heating byhigh-frequency currents will increase the radius ofcurvature without strain on the connection to the lead 6.

The iii-leading wire 6 is of tungsten 5.5 cms'. long by 0.3 cms. indiameter. To one end of this is butt welded a molybdenum wire 12 of thesame diameter about 1.3 cms. long. This is threaded to fit a threadedhole in the molybdenum member 9. The details of construction will bereadily apparent from It will thus be seen that we have provided aconstruction for leading current into the support collar for a controlelectrode which permits an'easy installation in thetube and whichprovides for a uniform distribution of the current to the controlelectrode. In accordance with the patent statutes, we have shown anddescribed one embodiment of our invention, butV various modificationsthereof will be apparent to those skilled in the art withoutdepartingfrom the principles which we have disclosed. Ve desire,therefore, that the appended claims shall be limited only by theirexpress terms and in accordance with the prior art.

We claim as our invention:

l. An electrical-discharge device for high frequency comprising acontainer enclosing a plurality of electrodes, an electrode assem- -larfor supporting it upon said stem, a conductor having a threaded portionsealed through the Wall of said container, flexible ribbon conductorsdiverging from said conductor and engaging said threaded portion forconnecting it to points spaced diametrically opposite on said electrode.

3. An electrical-discharge device for high frequency comprising acontainer having a reentrant stem, one of said electrodes having acollar for supporting it upon said stem, a tungsten conductor sealedthrough the Wall of said stem, and having an end portion comprising adifferent metal, a threaded portion upon said end portion and flexibleribbon conductors diverging from said conductor engaging said threadedportion and connecting it to diametrically opposite points on saidcollar.

In testimony whereof, vve have hereunto` subscribed our names this 7thday of October,

ILIA E. MOUROMTSEFF. GREGORY V. RYLSKY.

